Alkaline-biosurfactant-biopolymer process and its potential for enhancing oil recovery in Omani oil field

In present paper we ereport the evaluation and the application of Alkaline-Biosurfactant-Biopolymer (ABsBp) applications for enhancing oil recovery. Generally Alkaline-Surfactant-Polymer (ASP) studies have been carried out using chemical surfactants and polymers. This experimental investigation was performed to evaluate the possibility of using a biosurfactant and a biopolymer with sodium carbonate as an alkali for ASP flooding for the oil field. The candidate example reservoir was selected having favorable properties such as high permeability (500-1000 mD), low oil viscosity (20-25 cp), favorable total acid number (0.1 mg KOH/g oil) and high residual saturation (>20%). The current study was done to design an optimum composition of Alkali/Biosurfactant/Biopolymer (AbSbP) slug and apply it for enhancing oil recovery in both native reservoir cores and Berea sandstone core plugs. The interfacial tension (IFT) between various solutions containing alkali, biosurfactant and biopolymer was measured. Interfacial tension values in the range of 0.02-0.1mN/m were achieved at low biosurfactant and alkali concentrations. The interaction of the biopolymer with the brine, biosurfactant and alkali was investigated in terms of their effect on its viscosity at the reservoir temperature of 50°C. An AbSbP slug containing 1.1 wt.% sodium carbonate, 20 v/v% biosurfactant broth and 20 v/v% biopolymer broth was recommended for the final core flooding experiment. Core flooding experiments were conducted using reservoir cores and Berea cores by injecting the formulated AbS and AbSbP slugs after brine flooding. Maximum additional oil recovery obtained was 14% and 32% of oil initially in place (OIIP) from the reservoir cores and Berea cores respectively. Such difference in additional recovery was mainly due to the vast difference in the mineralogical composition of two rock types. This is the first report of application of Alkali-Biosurfactant-Biopolymer from Oman, showing additional oil from both native cores (from the Omani oil field) and Berea sandstone cores.